examples/src/main/java/org/apache/spark/examples/ml/JavaMulticlassLogisticRegressionWithElasticNetExample.java
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.spark.examples.ml;

// $example on$
import org.apache.spark.ml.classification.LogisticRegression;
import org.apache.spark.ml.classification.LogisticRegressionModel;
import org.apache.spark.ml.classification.LogisticRegressionTrainingSummary;
import org.apache.spark.sql.Dataset;
import org.apache.spark.sql.Row;
import org.apache.spark.sql.SparkSession;
// $example off$

public class JavaMulticlassLogisticRegressionWithElasticNetExample {
    public static void main(String[] args) {
        SparkSession spark = SparkSession
                .builder()
                .appName("JavaMulticlassLogisticRegressionWithElasticNetExample")
                .getOrCreate();

        // $example on$
        // Load training data
        Dataset<Row> training = spark.read().format("libsvm")
                .load("data/mllib/sample_multiclass_classification_data.txt");

        LogisticRegression lr = new LogisticRegression()
                .setMaxIter(10)
                .setRegParam(0.3)
                .setElasticNetParam(0.8);

        // Fit the model
        LogisticRegressionModel lrModel = lr.fit(training);

        // Print the coefficients and intercept for multinomial logistic regression
        System.out.println("Coefficients: \n"
                + lrModel.coefficientMatrix() + " \nIntercept: " + lrModel.interceptVector());
        LogisticRegressionTrainingSummary trainingSummary = lrModel.summary();

        // Obtain the loss per iteration.
        double[] objectiveHistory = trainingSummary.objectiveHistory();
        for (double lossPerIteration : objectiveHistory) {
            System.out.println(lossPerIteration);
        }

        // for multiclass, we can inspect metrics on a per-label basis
        System.out.println("False positive rate by label:");
        int i = 0;
        double[] fprLabel = trainingSummary.falsePositiveRateByLabel();
        for (double fpr : fprLabel) {
            System.out.println("label " + i + ": " + fpr);
            i++;
        }

        System.out.println("True positive rate by label:");
        i = 0;
        double[] tprLabel = trainingSummary.truePositiveRateByLabel();
        for (double tpr : tprLabel) {
            System.out.println("label " + i + ": " + tpr);
            i++;
        }

        System.out.println("Precision by label:");
        i = 0;
        double[] precLabel = trainingSummary.precisionByLabel();
        for (double prec : precLabel) {
            System.out.println("label " + i + ": " + prec);
            i++;
        }

        System.out.println("Recall by label:");
        i = 0;
        double[] recLabel = trainingSummary.recallByLabel();
        for (double rec : recLabel) {
            System.out.println("label " + i + ": " + rec);
            i++;
        }

        System.out.println("F-measure by label:");
        i = 0;
        double[] fLabel = trainingSummary.fMeasureByLabel();
        for (double f : fLabel) {
            System.out.println("label " + i + ": " + f);
            i++;
        }

        double accuracy = trainingSummary.accuracy();
        double falsePositiveRate = trainingSummary.weightedFalsePositiveRate();
        double truePositiveRate = trainingSummary.weightedTruePositiveRate();
        double fMeasure = trainingSummary.weightedFMeasure();
        double precision = trainingSummary.weightedPrecision();
        double recall = trainingSummary.weightedRecall();
        System.out.println("Accuracy: " + accuracy);
        System.out.println("FPR: " + falsePositiveRate);
        System.out.println("TPR: " + truePositiveRate);
        System.out.println("F-measure: " + fMeasure);
        System.out.println("Precision: " + precision);
        System.out.println("Recall: " + recall);
        // $example off$

        spark.stop();
    }
}
